This invention relates to an image forming method for a copying machine using an automatic document feeder and double face printer, for example.
In recent years, in an image forming apparatus, an attempt is made to shorten time for printing paper to reach the printing position and enhance the copying speed by feeding printing paper at the same time as feeding of a document in a case where an automatic document feeder (ADF) is used to effect the continuous copying operation.
In this case, if a document jam occurs during the document feeding process by use of the ADF and normal image reading cannot be attained, printing paper which is already started to be fed is also jammed if it is stopped at the place. Therefore, the printing paper is discharged as a failure in printing in order to prevent the paper jam.
At this time, the document fed is not placed in the normal position. Therefore, if a scanned image is output, there occurs a possibility that an image is only partly printed on the printing paper or an image of the preceding document is printed on the printing paper. In order to prevent the user from being disturbed, the image is not output, only the paper is fed and, as a result, a blank sheet of paper is obtained. Therefore, in the specified discharging destination, one or more blank sheets of paper are discharged.
When double face printing is effected by use of a double face printer (perfecting machine) and if blank printing occurs by a document jam or the like, paper printed in the blank state is stacked (stored) in the double face printer. As the result, since one page of blank paper is inserted, the normal relation between the pages on the front and rear surfaces cannot be obtained.
For example, in a case where one set of documents including single-face documents of six pages are printed on printing paper by double face printing by use of a copying machine having no memory for storing read images, the documents are printed with the first page/second page, third page/fourth page, fifth page/sixth page printed on the front/rear surfaces of respective sheets of printing paper as shown at (a) to (c) in FIG. 25 if the normal printing is effected.
If the document of third page is jammed to cause abnormal paper feeding and a failure in reading of the document occurs, the first page/second page, abnormal image (blank paper)/third page, fourth page/fifth page, sixth page/blank page are obtained on the front/rear surfaces of respective sheets of printing paper as shown at (a) to (d) in FIG. 26. Therefore, in comparison with the printing result of the correct double-face printing, the relation between the pages on the front and rear surfaces is reversed before and after the page of abnormal image (blank paper). This also occurs when double-face documents are printed by double face printing.
Further, in the case of a digital copying machine having a memory for storing read images, images of the documents read by a scanner section can be temporarily stored and held in the memory. Therefore, it is possible to print the images in an order different from the reading order in which the images are read by the scanner section 4. Further, the images stored in the memory can be printed after all of the documents are read. However, in this case, it is necessary to substantially simultaneously effect the paper feeding operation of a document, scanning operation and printing operation so as to enhance the copying speed.
In the digital copying machine of first-in first-out (FIFO) system having the above memory, for first feeding paper which is first stacked by the double face printer, the printing for the first page, third page and fifth page is effected in this order at the same time as reading of the documents when single-face documents of plural pages are printed by double face printing. In this case, images of the documents read are stored into the memory, and at the same time, sheets of paper on one-side surfaces of which images of odd pages of the first page, third page and fifth page are printed are stacked in the double face printer.
Then, the sheets of paper on one-side surfaces of which images of the first page, third page and fifth page are printed are sequentially fed out from the double face printer, document images of the second page, fourth page and sixth page are printed on the rear surfaces of the sheets of printing paper and the sheets of printing paper are discharged. As a result, the first page/second page, third page/fourth page, fifth page/sixth page are printed on the front/rear surfaces of the respective sheets of paper as shown at (a) to (c) in FIG. 25.
Thus, wasting time caused by the mechanical structure is reduced and the copying speed is enhanced. In this system, if the document of third page is jammed to cause abnormal paper feeding and a failure in reading of the document occurs, images printed on the one-side surfaces of the sheets of paper stacked in the double face printer are the first page, abnormal image (blank paper), third page and fifth page, and if printing is made on the rear surfaces of the sheets of paper, the first page/second page, abnormal image (blank page)/fourth page, third page/sixth page, fifth page/blank page are obtained on the front/rear surfaces of the respective sheets of paper as shown at (a) to (d) in FIG. 27. The same result may be obtained in the case of double-face document.
In a device of first-in last-out (FILO) system having a memory for storing images, for first feeding paper which is last stacked by the double face printer, document images are printed on the front surfaces of sheets of paper in an order of the second page, fourth page, sixth page of the documents and the sheets of paper are stacked on the double face printer. Then, document images are printed on the rear surfaces of the sheets of paper stacked in the double face printer in an order of the fifth page, third page and first page and the sheets of paper are discharged. As a result, the sixth page/fifth page, fourth page/third page, second page/first page are printed on the front/rear surfaces of the respective sheets of paper as shown at (a) to (c) in FIG. 28.
In this case, if a failure in reading of the document of third page occurs, for example, images are printed on sheets of paper stacked in the double face printer in an order of the second page, abnormal image (blank paper), fourth page and sixth page. Then, if images are printed on the rear surfaces of the stacked sheets of paper, the sixth page/fifth page, abnormal image (blank paper)/third page, fourth page/first page, second page/blank paper are printed on the front/rear surfaces of the respective sheets of paper as shown at (a) to (d) in FIG. 29 and the relation between the pages on the front and rear surfaces becomes strange.
As described above, if a document jam occurs in the automatic document feeder when the double face printing is effected by use of the automatic document feeder, printing paper which is started to be fed at the same time is stacked in the double face printer with the surface thereof kept in a blank state. Since the paper stacked in the blank state is dealt with in the same manner as another sheet of paper which has been correctly printed and stacked when the printing for the rear surfaces thereof is started, the printing is made on the rear surface of the blank paper and the relation between the succeeding pages of the front and rear surfaces becomes strange.
An object of this invention is to provide an image forming method for dealing with paper on which an erroneously read image is printed in the same manner as correctly printed paper when the double face printing is made and effecting the double face printing operation with the pages of the front and rear surfaces of sheets of paper set in order without shifting the pages of the front and rear surfaces of the sheets of paper.
According to one aspect of this invention there is provided an image forming method effected by use of an image forming apparatus including reading means for reading plural pages of documents in the unit of page, image forming means for forming images read in the unit of page by use of the reading means on first and second surfaces of an image forming medium, discharging means for discharging the image forming medium on which the images are formed by the image forming means, first supply means for supplying the image forming medium received in a paper feeding section to the image forming means, and second supply means for supplying the image forming medium on the first surface of which the image is formed by the image forming means to the image forming means with the first and second surfaces of the image forming medium reversed, comprising the steps of effecting a process for reading each of the documents of odd pages by use of the reading means, forming the image on the first surface of the image forming medium by use of the image forming means and supplying the image forming medium to the second supply means when document images of plural pages are formed on the first and second surfaces of the image forming media; determining whether reading of an image of the document to be formed on the first surface of the image forming medium is abnormal or not when the processing step is effected; reading the document of even page by use of the reading means if it is determined in the determining step that abnormal reading of the document does not occur, then supplying the image forming medium processed by the processing step to the image forming means by the second supply means, forming the image on the second surface of the image forming medium and discharging the image forming medium; and discharging the image forming medium by the discharging means without forming the image on the second surface of the image forming medium processed in the processing step if it is determined in the determining step that abnormal reading of the document occurs and re-starting the processing step starting from the document which is determined to be abnormally read.
According to another aspect of this invention, there is provided an image forming method effected by use of an image forming apparatus including reading means for reading plural pages of documents in the unit of page, first storage means for storing images of the documents of at least even pages read by the reading means, image forming means for forming images read in the unit of page by use of the reading means on first and second surfaces of an image forming medium, discharging means for discharging the image forming medium on which the images are formed by the image forming means, first supply means for supplying the image forming medium received in a paper feeding section to the image forming means, and second supply means for supplying the image forming medium to the image forming means with the first and second surfaces thereof reversed in the order in which the image forming medium is earlier received into the receiving section after the image forming media on which the images are formed by the image forming means are temporarily received into the receiving section, comprising the steps of effecting a process for reading the plural pages of documents by use of the reading means, forming the images of odd pages on the first surfaces of the image forming media and storing the image forming media in the receiving section, and storing the images of even pages into the first storage means when images of the plural pages of documents are formed on the first and second surfaces of the image forming media; determining whether reading of an image of the document to be formed on the first surface of the image forming medium is abnormal or not when the processing step is effected; storing abnormal reading into second storage means based on the order in which the image forming media are received into the receiving section when it is determined in the determining step that abnormal reading of the document occurs; receiving the image forming medium now processed into the receiving section when it is determined in the determining step that abnormal reading of the document occurs and then re-starting the process starting from the document which is determined to be abnormally read; and sequentially supplying the image forming media stored in the receiving section to the image forming means by the second supply means when the process for all of the documents of odd pages is completed by the above process, sequentially forming the images of the documents of even pages of the reading order stored in the first storage means on the second surfaces of the image forming media for which abnormal reading is not stored in the second storage means by use of the image forming means and discharging the image forming media by use of the discharging means, and discharging the image forming media for which abnormal reading is stored in the second storage means by use of the discharging means without forming the images by the image forming means.
According to still another aspect of this invention, there is provided an image forming method effected by use of an image forming apparatus including reading means for reading plural pages of documents in the unit of page, first storage means for storing images of the documents of at least odd pages read by the reading means, image forming means for forming images read in the unit of page by use of the reading means on first and second surfaces of an image forming medium, discharging means for discharging the image forming medium on which the images are formed by the image forming means, first supply means for supplying the image forming medium received in a paper feeding section to the image forming means, and second supply means for supplying the image forming medium to the image forming means with the first and second surfaces thereof reversed in the order in which the image forming medium is later received into the receiving section after the image forming media on which the images are formed by the image forming means are temporarily received into the receiving section, comprising the steps of effecting a process for sequentially reading the plural pages of documents by use of the reading means, storing images of the odd pages of documents into the first storage section, and forming the images of the even pages of documents on the first surfaces of the image forming media and storing the image forming media in the receiving section when images of the plural pages of documents are formed on the first and second surfaces of the image forming media; determining whether reading of an image of the even page of document to be formed on the first surface of the image forming medium is abnormal or not when the above processing step is effected; storing abnormal reading into second storage means based on the order in which the image forming media are received into the receiving section when it is determined in the determining step that abnormal reading of the document occurs; receiving the image forming medium now processed into the receiving section when it is determined in the determining step that abnormal reading of the document occurs and then re-starting the process starting from the document which is determined to be abnormally read; sequentially supplying the image forming media stored in the receiving section to the image forming means by the second supply means when the process for all of the documents of even pages is completed by the above process; sequentially forming the images of the documents of odd pages set in a reverse order of the reading order stored in the first storage means on the second surfaces of the image forming media for which abnormal reading is not stored in the second storage means by use of the image forming means and discharging the image forming media by use of the discharging means; and discharging the image forming media for which abnormal reading is stored in the second storage means by use of the discharging means without forming the images on the second surfaces thereof by the image forming means.
According to another aspect of this invention, there is provided an image forming method effected by use of an image forming apparatus including reading means for reading plural pages of documents in the unit of page, storage means for storing images of the documents of at least alternate pages read by the reading means, image forming means for forming images read in the unit of page by use of the reading means on first and second surfaces of an image forming medium, first supply means for supplying the image forming medium received in a paper feeding section to the image forming means, and second supply means for receiving the image forming media on the first surfaces of which the images are formed by the image forming means into a temporary receiving section and then supplying the image forming medium received in the receiving section to the image forming means with the first and second surfaces thereof reversed, comprising a fist step of sequentially reading the plural pages of documents by use of the reading means, forming images of the documents of alternate pages on the first surfaces of the image forming media, and storing images of the documents of alternate pages which are different from the images of the documents of alternate pages formed on the first surfaces of the image forming media into the storage means in a reading order when images of the plural pages of documents are formed on the first and second surfaces of the image forming media; a second step of sequentially supplying the image forming media received in the receiving section to the image forming means by the second supply means and forming images stored in the storage means on the second surfaces of the image forming media in an order in which the image forming media are supplied when a process in the first step is completed; a step of receiving the image forming medium now processed into the receiving section when abnormal reading of the document occurs at the time of formation of the image on the first surface in the first step and re-starting the process of the first step starting from the document of a page for which abnormal reading has occurred; and a step of shifting the page of abnormal reading and succeeding pages by one page according to an order in which the image forming media are supplied without forming the image of the page stored in the storage means when the image forming medium which is stored in the receiving section and for which abnormal reading occurs at the time of image formation is supplied at the time of effecting the process of the second step after the process of the first step is re-started.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.